describe the "trick" which has been worth a hundred marks a year to the Pardoner

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The Pardoner charismatically earns the trust of his parishioners, and then convinces them he has special relics that can absolve them of sin if money is given to them. They are not actually relics, but sinful folks want absolution and so throw money at the relics. By convincing them they have been forgiven, he has done nothing but say some words and now can gather the money for himself.